No description available.

No description available.

Three behavioural mutants of A. tumefaciens C58C1 (mot-l, mot-12 and fla-15) generated by transposon (Tn5) mutagenesis were studied. Analysis was initially at the molecular level, as a cosmid, pDUB1900, from a representative genomic library of C58C1 had been isolated that complemented the mutants. A region of 8624 nucleotides to which the Tn5 insertion sites of the three mutants had been mapped was sequenced completely in both directions. The comparison of this sequence with sequence databases and other computer analyses revealed six flagellar gene homologues (flgI,flgH,fliP,flaA,flaB,flaC), three open reading frames (ORFA, B and C) with no significant sequence identity to any open reading frames in the databases and the partial sequence of the flagellar gene homologue flgG. Computer analysis also showed that theflgH,flgI andfliP homologues, and ORFs A, B and C, could form the downstream region of a larger operon involved in chemotactic and motility functions. However putative transcription signals were also found within the operon. A new mutant (MANl) was created in the last gene (fliP) of the putative operon to investigate the function of possible transcription signals in the open reading frame immediately upstream of it (ORFC). The mot-12 mutant phenotype of fully synthesised but paralysed flagella is brought about by the insertion of Tn5 in ORFC. ORFC contains a possible promoter for fliP. The Tn5 insertion in ORFC should have polar effects upon the expression of fliP, unless the putative promoter can cause expression of fliP. The MANl mutant had a flagella-less phenotype. FliP in other bacteria is required early in the synthesis of flagella and the null phenotype is/7a-. Thus for flagella to be present in mot-12 suggests fliP must have a promoter. The ORFC sequence is highly conserved in R. meliloti and the overall regulation of these flagellar gene homologues may be as an operon with other regulatory signals. Evidence from other operons (including motility operons) with multiple transcription signals is discussed. The flaABC homologues were multiple copies of the gene encoding the flagellin protein of the flagellum. The mot-l phenotype of severely truncated filaments was caused by a Tn5 insertion in flaA. Analysis of the sequence showed flaABC to each have transcription signals that could lead to separate transcription. Transcription analysis by Northern blotting showed flaA to be transcribed monocistronically. Flagella were isolated from A. twnefaciens and the flagellins separated by SDS-PAGE. The migrated distances (relative to those of markers) was not as predicted from the nucleotide sequence. This anomaly could be caused by unequivalent binding of SDS or post-translational modification of FlaA. The A. tumefaciens flagellar genes were most similar to those of R. meliloti. However A. tumefaciens flagella do not exhibit the characteristic cross-hatching of the complex flagella of R. meliloti. This study also showed A. tumefaciens flagella not to be dependent on divalent cations for subunit associations unlike R. meliloti. These properties of A. tumefaciens flagella were similar to those of R. leguminosarum.The open reading frames found were isolated, radiolabelled and used as probesagainst Southern blots containing chromosomal DNA from a variety of soil bacteria, and cosmids known to contain motility genes in R. meliloti. Hybridisation revealed homologous DNA sequences in a number of these bacteria. All the A. tumefaciens open reading frames hybridised to homologous DNA in R. meliloti and are found in the same order in both species. This suggests that there are similarities at the molecular level in motility and chemotaxis functions between R. meliloti and A. tumefaciens as well as in the patterns of chemotaxis and motility observed previously.

No description available.

Bibliography: leaves 322-368. / xii, 368 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Presents studies relating to normal and disordered gastric motility and the role of the gastrointestinal tract in appetite regulation in humans. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 1997

Bibliography: leaves 206-251. / xii, 251 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The motor and sensory interactions between nutrients and proximal gut in humans are not well understood, despite the pivotal importance of these interactions on appetite, absorption and thus, nutrition. In part, this lack of knowledge results from technical difficulties in studying motor function in the human gut. In particular, the inability to continuously measure intraluminal flow with any degree of temporal resolution, has impeded progress in this field. The studies described in this thesis focus on nutrient-gut interactions, and also on the development of novel methodologies aimed at advancing the understanding and interpretation of the relationships between intraluminal pressures and flows. / Thesis (Ph.D.)--University of Adelaide, Dept. of Medicine, 2000

Includes bibliographical references (leaves 349-440). / 440 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The broad areas addressed are: the effect of physiological changes in the blood glucose concentration in the regulation of gastroduodenal motor and sensory function; the effect of acute hyperglycaemia on gastric motor and sensory function in patients with diabetes mellitus and the motor response to prokinetic therapy; the relationships between small intestinal nutrient exposure, gastrointestinal peptide hormone release, antropyloric motility and appetite; and, the effect of aging on the proximal gastric response to distension and food intake. / Thesis (Ph.D.)--Adelaide University, Dept. of Medicine, 2001

Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [79]-83).

Thesis (doctoral)--Ludwig Maximilians-Universität zu München, 1978.

Gastrointestinal motility investigations involve the study of the motions of the bowel. Their goal is to understand the nature of the physical interactions that take place between the gut wall and its contents in both health and disease. The aim of this project was to develop a computerised system for the measurement, inspection, analysis and collation of prolonged, ambulatory manometric records from within the human small bowel. This was planned to evolve from existing analogue techniques using a specially commissioned digital data-logger. This thesis describes the testing of the data-logger by comparison with an accepted standard technique, investigating its long-term stability and the effect of different sampling rates. Then the development of a means of detecting intestinal contractions with minimal artefact is described. When validated against 6 experienced human observers the program had a sensitivity of between 84-95 % and a positive predictability of 98% in a noise free signal falling to 37% in a signal containing many movement artifacts and few contractions. The inter- and intra-observers response was found to be variable displaying a high degree of subjectivity in their assessment with respect to the computer. Further methods for the classification of intestinal activity in the temporal domain such as contraction frequency and the occurrence of clusters of contractions are described. A new parameter, Psw is proposed which provides an indication of the relative inter-contractile separations. The effect of meals and disease on Psw, contraction and cluster incidence is investigated and all three parameters are found to be markedly affected by feeding. A program for the identification of contractile propagation across adjacent sites is described, with reference to both a computer model and data from healthy subjects. A cross-correlation method is devised for the accurate assessment of propagation velocities. Finally, the form of database currently used for the clinical reporting of routine small bowel motility investigations is described with suggestions for improvements and additions to this database which are planned.